1. Field of the Invention
The present invention relates to an anti-fogging film having a good durability.
The anti-fogging film of the present invention is advantageously used for window panes, window glasses of airplanes, and front and rear window and window shield glasses of automobiles.
2. Description of the Related Art
Plastic materials and inorganic glasses are widely used as various articles such as window panes, mirrors, eyeglass lenses and goggles, while retaining a transparency, but, when these materials are placed under high-temperature and high-humidity conditions or at interfacial boundaries where the differences of the temperature and humidity are large, the surface is fogged or often scratched.
Accordingly, attempts to impart an anti-fogging property and durability to these articles have been proposed.
For example, U.S. Pat. No. 4,127,682 proposes the use of polyvinyl alcohol for imparting an anti-fogging property and durability.
It is known that polyvinyl alcohol is crosslinked with finely divided silica to give a water-resistant coating (U.S. Pat. No. 3,773,776).
Furthermore, a curable coating composition comprising a polyvinyl alcohol/silica complex as the main component has been proposed (U.S. Pat. No. 4,016,129).
Moreover, U.S. Pat. No. 4,478,909 proposes an anti-fogging film having an improved durability, and having a multilayer structure composed of polyvinyl alcohol, finely divided silica and an organic silicon compound and/or a hydrolysis product thereof, wherein the content of silica in a lower layer is larger than that in the topmost surface layer.